Process for treating rubber articles and product



3 i Y I I or Michigan.

ic the-objectionable feature of having small almost andcu'redandsubsequently processed in the usual 65 "15 pose for which it was.designed andconstructed. t e I have found this to preferab1e,.be

7 0 of time, it has been found that the rubber has isulphonated Castor0115 If desired, the, hygro 7 T13! resistance to tear. The new productis capable Patented Nov. 14, 1933 p V t i 1,935,165 7 PROCESS FORTREATING, RUBBER j g a ARTICLES AND PRODUCT WilliamiA, Steinle, Detroit,Mioh'g'assignor' to Morgan '& Wright, Detroit, Mich, a corporation NoDrawing: Application January 55,1931- r, SerialNo, 506,314

-6 Claims." (01. 18 -58) This invention relates to theproduction ofample which'j-ischosen forillustrative purposes strong and imperviousrubber materials such as merely: V

a L automobile inner tubes and contemplates a new 1 A suitable mandrel,forinstance in the genand improved procssfor making such materials. eralshape of an inner tube for automobile tires, FIn the manufacture ofrubber articles such as is pp 'in a latex COmDOSitiQTI for a pe Of 60.inflatable bodies, fromlatex or artificial disperr me? sufiicient for te requ ed t c e of sions of; rubber, it has beenfoundthat the finp s tto form, after which it s dried for a few ished product althoughstronger than tubes manut d immerfied a a a glycerine bathufactured byother processes, sometimes possesses T mandrel is Withdrawn andfilmdlied infinitesimal pinholes therein through which, a for formationi a i n r; b It when the article is inflated, the gaseous inflatingShould be noted that the rubber materlal y be medium slowlyleaks,thereby reducing th man artificial dispersion ofrubber instead of latexciencyof the article .in accomplishing the purthat a dififerential inpressure ay, d i

Under constant conditions of temperature and employed both during thelateX pp d y dryness, this slight porosity increases with the i DP QODBI'atiOIIS- stead of glycerine', age oftheinflatable'body. Moreover,after storother hygroscopic materials may used suychtas age of sucharticles'for any considerable period ethylene glycol: ethanol amines andnaturallor scopic material may be added to the, rubber dispersion itselfand its incorporation-in the deposited film'th'us eifectuated by dippingtherein, but I have found it commercially expedient to dip a form into adispersion"and then subject it to 30 the action of the hygroscopicagent. 'Rep'eat'ed and aIternateIdippings may be made as desired.

As a specific example of the procedure including the principles of thisinvention, the following is illustrative: a 5

A latex compound was obtained in accordance with the following formula:

lost some of its original flexibility. and softness and hasbecomelslightly dry and hard and there'- by lost some of its resistance totearing. These disadvantages have been overcome by the pres entinvention which makes it possible to imanufacture a rubberarticle ofgreat strengthwhich is less-porous and more resistant to leaks thanarticles of the same character heretofore known and which possessesgreater and more permanent of being stored for substantial periods oftime without apparent drying or hardening and without loss of its powerto resist tearing action. 1 Parts 685 The invention comprisesgenerically the in- Rubber (as latex) 100 1 corporation of a hygroscopicsoftening agent into Zinc oxide 5 the rubber stock in order to insurethe absorp- Whiting tion and permanent retention therein of a smallSpindle Oil 10 percentage of moisture. Although I do not know Sulphur 3.the precise principle which explains the present Paraffin 1 invention, Ibelieve that the hygroscopic mate-' Heptene 5 rial, having a tendency torepel rubber and not i to mix therewith, bleeds to the surface of theAmmoma Sodium polysulphide 50% solution--- ,7. 50

coagulated and cured film where. it remains by the concurrent action ofthe polar attraction of (Into the r t compound above Set out aporousgloo V one end of each molecule to the rubber mass and form wasdipped for 5 minutes under a difierem the 9 9 5 attractton exerted the hj tial pressure, or until a deposit is formed. which scopic liquid inthe minute pores of interstlces or will have a cured gauge ofapproximately 060 the rubber- The hygroscopic material, having. The formwas removed and allowed to stand so the capacity to ai a uniformmoisture o under vacuum for 5 minutes. It was then dipped e t i s s thepresence of moisture thrOughOllt into a solution of glycerine and waterfor one the rubber mass and renders it softer and'jbetter minute,afterwhich it was removed and allowed able to resist tearing and toresist the passage to dry while still under vacuum for about an hour ofgases therethrough. at room temperature. The vacuum was then 5'5; Theinvention is typified by the following exbroken and the tube wasdried at170 F. for 50 minutes and then cured for 65 minutes at260 F. in steam atatmospheric pressure.

I have found the following advantageous changes in the properties ofrubber inner tube stock have resulted by the practice of this invention.An inner tube made by present methods was compared with one madesimultaneously by the method included in this invention, and after aspecified period the tear strength and porosity of each tube stock wasmeasured:

Resistance to tear Resistance to tear after treatment in of stocktreated Percent increase in accordance with strengthasshown g z gfiig yi n v e n t i o n by tearresistance p (pounds) 24.8 41.8 68'percentPorosity or air leak Porosity or air leak of stock after of stock,treated treatment with 'in regular mam Percent (lecreasem thisinvention porosity or air net (loss of p (105s i pressure l sure mpounds in pounds per 5 wegk) 'week) 3.78 3.02 percent The porosity testindicates the average loss in pounds for each week, the tires havingbeen pumped to a specified pressure at the end of each week. Y

In the material produced by the use of the process of this invention theglycerine absorbed may be from 5 to 12% depending on the condi-.

tions, of treatment. 7

.The illustrative example is to be considered as such and does not limitthe scope or" the present invention'which obviously may be applied tothe production of other articles than automobile inner tubes. 40

v In addition to the materials mentioned herein, I contemplate theaddition of other kinds of compounding ingredients in a deposited rubberfilm in the mannerherein. set forth. V

Having thus described my invention, what I claim and desire to protectby Letters Patent is: 1. A process for increasing the gas impermeabilityand tear resistance of rubber deposited directly from aqueousdispersions which comprises diffusing a fluid hygroscopic material intothe deposited rubber under differential pressure, andpermanentlyretaining said material in the rubber. V

2. A process for increasing the gas impermeability and tear resistanceof rubber deposited di rectly from'aqueous dispersions which comprisesdiirusing into the deposited rubber under differential pressure a fluidhygroscopic material selected from the group consisting of glycerin,

ethylene glycols, ethanol amines, and natural or sulphonated non-dryingoils, and permanently retaining said material in the rubber. 3. Aprocess for increasing the gas impermea- .bility and tear resistance ofrubber deposited directly from aqueous dispersions which comprisesdifiusing into the deposited rubber under differential pressure a fluidhygroscopic material comprising at least two methylene groups eachattachedto hydroxyl, and permanently retaining I said material in therubber. i Y 1 4; A process for increasing the gas impermea' bility andtear resistance of rubberdeposited -directly from aqueous dispersionsWhichcomprises diffusing glycerin into the deposited rubber underdifferential pressure, and permanently retaining saidglycerin in therubber." a i 5. A process for increasing thegas impermeability and tearresistance or rubber deposited directly frorn'aqueous dispersions whichcomprises forming a deposit of solids from an aqueous dispersion ofrubber, superficiallydrying the deposit, diffusing a fiuid hygroscopicagent into-the deposit, and permanently retainingit.therein dry ing andvulcanizing. i

' 6. A process for increasing the gasimperme'a bility and tearresistance of rubberdeposited directly from aqueous dispersions-whichcomprises forming a deposit of solids from an aqueous dis persion ofrubber, superficially'drying the deposit, treating the deposit under'diiferential' pressure with a solution of; glycerinand permanentlyretaining the glycerin in the deposit, drying, and vulcanizing. v a rWILLIAM A. STEINLE.

